refactor(src): 移除未使用的 reactivity 模块

- 从 src/index.ts 中移除了对 reactivity 模块的导出
- 删除了 src/reactivity.ts 文件

Author: wardenfeng

src/index.ts

@@ -38,8 +38,6 @@ export * from "./data/VertexState";
 export * from "./data/Viewport";
 export * from "./data/WriteBuffer";
 
-export * from "./reactivity";
-
 export * from "./internal/BufferBindingInfo";
 
 export * from "./types/TypedArray";